Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

15406 results found.

  1. GRB 250814A: COLIBRÍ optical upper limit
  2. GRB 250813A: AstroSat CZTI detection
  3. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  4. GRB 250813B: EP-FXT counterpart detection
  5. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  6. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  7. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  8. GRB 250813B: SVOM detection of a bright long burst
  9. GRB 250812A: NTT spectroscopic redshift z = 2.57
  10. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  11. EP250812a: NOT, NTT, and GS observations
  12. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  13. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 250812A: EP-FXT counterpart detection
  15. GRB 250812A: Swift ToO observations
  16. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  17. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 250812A: SVOM detection of a faint long burst
  19. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  20. GRB 250808A: Fermi GBM Observation
  21. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  22. GRB 250808A: SVOM detection of a long burst
  23. Konus-Wind detection of GRB 250807A
  24. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 250806A: SVOM/ECLAIRs refined analysis
  26. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  27. GRB 250804B: Insight-HXMT detection
  28. GRB 250807A: SVOM/GRM observation
  29. GRB 250807A: AstroSat CZTI detection of bright long burst
  30. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  31. EP250806a: Upper limit from Fermi-GBM Observations
  32. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 250805A: Kilonova-Catcher optical upper limits
  34. EP250806a:SVOM/VT refined analysis
  35. GRB 250806A: Swift/UVOT U-band detection
  36. EP250806a: Liverpool telescope optical upper limit
  37. GRB 250806A: EP-FXT observation
  38. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  39. GRB 250806A: J-band upper limit from WINTER
  40. GRB 250806A: KAIT optical upper limit
  41. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 250806A: SVOM detection of a soft burst
  43. GRB 250805A: ESO/VLT observations
  44. GRB 250804C: AstroSat CZTI detection of a long burst
  45. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 250804B: Tiled Swift observations
  47. GRB 250804B: SVOM/GRM observation of a short burst
  48. The EP-WXT trigger 01709198251 is likely a flaring star
  49. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  50. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  51. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  52. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  53. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  54. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  55. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  56. GRB 250725A: AstroSat CZTI detection
  57. GRB 250725A: PRIME near-infrared observations
  58. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  59. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  60. GRB: Clarification on Gamma-Ray Burst Naming Convention
  61. GRB 250727A: SVOM/ECLAIRs refined analysis
  62. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  63. GRB 250728A: Swift ToO observations
  64. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  65. GRB 250727A: AST3-2 Upper limit
  66. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  67. GRB 250727A: SVOM detection of a burst
  68. The EP-WXT trigger 01709195487 is likely a flaring star
  69. Konus-Wind detection of GRB 250725A
  70. GRB 250725A: SVOM/GRM observation
  71. GRB 250725A: Fermi-LAT detection
  72. GRB 250725A: BOOTES-7 early optical detection
  73. GRB 250725A: SVOM/VT optical candidate
  74. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  75. GRB 250713A : SVOM/ECLAIRs refined analysis
  76. GRB 250717B: SVOM/GRM observation
  77. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  78. GRB 250721A: Tiled Swift observations
  79. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  80. GRB 250717B: Swift ToO observations
  81. GRB 270713A: Kitab and AbAO Optical Observations
  82. GRB 250717B: Fermi GBM Observation
  83. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  84. Konus-Wind detection of GRB 250716A
  85. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  86. GRB 250716A: Swift ToO observations
  87. GRB 250714A: SVOM/GRM observation
  88. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  89. GRB 250713A: Mephisto optical upper limits
  90. EP250711a: COLIBRÍ continuous optical observations
  91. GRB 250713A: SVOM detection of a long burst
  92. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  93. GRB 250711A: SVOM/GRM observation
  94. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  95. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  96. GRB 250704A: GRANDMA observations
  97. GRB 250704A: SVOM/ECLAIRs refined analysis
  98. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  99. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  100. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov